Providers, policymakers and researchers concerned with mental health services repeatedly make reference to the importance of continuity of care, particularly for persons with severe mental disorders who have multiple and ongoing service needs. However, research on continuity of care has been impeded by poor measurement. Thus at present the importance of continuity of care remains an untested assumption rather than a statement supported by empirical evidence. The proposed project will develop a formal, quantitative measure of continuity of care in mental health services using data generated through an ethnographic study. The measure will be a structured interview designed for use with consumers as respondents. The project takes place in three stages. The first is the collection of ethnographic data and the analysis of these data to produce the first draft of the interview. The second stage is a pilot test in which the interview is administered to 30 persons with severe mental disorders. Preliminary psychometric analyses will be carried out using the pilot test data and revisions to the interview made as needed. The project's third stage is a field test and psychometric analyses. Four hundred persons with severe mental disorders will be interviewed and the resulting data used in evaluating the psychometric properties of the interview. The plan for psychometric analysis calls for examination of: (1) data quality, (2) summated-rating scaling assumptions, (3) item- discriminant validity and scaling success rates, (4) reliability of scale scores, (5) features of score distributions, and (6) construct validity. A number of sources of bias that might affect validity will also be examined.